Method of color printing



Patented May 27, 1941 METHOD or coma PRINTING,

John J. Ormond, Boston, Mass, assignor of twothirds to Joseph D. Ramsey,Boston, Mass.

No Drawing. Application October 2, 1940, Serial No. 359,393

12 Claims.

This invention relates to improvements in printing and more especiallyto novel methods of multi-color printing.

In multi-color printing, considerable diificulty is experienced inbringing together a number of differently colored printing inks whileall of the inks are in a wet state. This is true of 'juxtaposedmulti-color printing and particularly so of blended multi-colorprinting. The differently colored inks tend to run .and blur, resultingin unsatisfactory quality of work unless great care is exercised. It isnow customary to resort to expensive and time consuming drying stepswhereby .each color printed is dried before another color is associatedwith it. It is also necessary in present blended multi-color printing toemploy inks of a somewhat transparent nature which combine with a drycolor to provide a blended effect. This adds further expense andlimitation to the process and fails to provide a true blended coloreffect such as results from blending a number of colors in a wet state.

It is a chief object of the present invention to improve methods ofprinting and to devise means for facilitating multi-color printing witha view to eliminating to a large extent specific drying operations inconnection with color printing, and to making possible the blending of anumber of colored inks, in a wet state, to form a blended color imagewhich may be printed down in one operation. The invention also aims tobroaden the scope of printing inks and printing members and to provideinterchangeability in connection therewith. A still further object ofthe invention is to increase the scope of intaglio and letterpressprinting processes and to combine these and other processes with ofi'setprinting procedures to present cheap, fast, and efficient printing.

The nature of the invention and its objects will be more fullyunderstood from the following discussion.

In the usual method of multi-color printing, a number of colors areseparately printed with each color being allowed to dry before asucceeding color is applied. This may be eifected by direct or offsetprinting means for each color, and in the case of blended color printingthe several ink layers are superimposed over one another on the surfaceto be printed. Separate application of colors and drying requireconsiderable time which greatly increases the expense of color work. Ifan offset process is employed, separate offset rolls for each color arealso necessary. In allowing a color to dry, the .tint of that color ischanged and therefore the succeeding color must be of a shade tocompensate for this inobtaining a desired blend of color. As a result atrue blending of the colors, which would normally result fronrblendingtogether two colored inks in a wet state, does not occur. if;

In accordance with one embodiment ,of the method of the invention,three. colorplates" are prepared in accordance with the three colorproc-" ess. These plates are of the intaglio type and are inked withinks of the primary colors, yellow, blue and red, each .ofwhich has aspecial-absorptive character. The plates are arranged in some convenientmanner such that they are in register with one another; Forexample, theymay be locked up in a chase. Thereafter a resilient transfermember,,registered in gear with the chase, is passed over the plates inone continuous operation to pick up selective amounts of each of thecolors and bring them together in a wet state one upon another. Thetransfer preferably collects the inks in the sequence noted above inwhich the yellow ink is first, the blue ink is second and the red ink isthird. The superimposed wet inks, making up a colored image on thetransfer member, are then offset on to a surface to be printed toprovidea blended color print.

The film of yellow ink, first applied on the transfer surface, functionsto attract and pick up blue ink and to absorb the blue ink withinitself. Similarly, the yellow ink and blue ink absorbed in yellow ink,function to pick up and absorb red ink. The inks are completely absorbedin one another which allows a blending action to occur all the waythrough the superimposed films of ink and provide the same blended colorvalues adjacent the transfer roll surface as those present at theoutside of the combined ink films. This is essential to the offsettingoperation since the blended color film side adjacent the transfersurface becomes the outside of the offset print. In comparison with theconventionalcolor method outlined above, it will be observed that all ofthe inks are blended 'in a wet state, blending occurs on a transfermember instead of the surface to f be printed, only one transfer oroff-set member is employed in place of separate oflset members for eachcolor, and no drying period is necessary at any point.

Thenovel procedures and results noted are due in large part to thecomposition and interrelated I character of the inks. They are allcompounded with some common base, as a drying oil. or other suitablevehicle, which renders them attractive to one another, and promotesquick liq; character. The inks vary in consistency in duated manner withthe first ink, in a series of colored inks, being the heaviest and theremaining inks being of progressively thinner consistencies. This allowsthe inks to be absorbed in one another when brought together insuperimposed relation in the proper sequence. The inks may also becompounded with reagents directed to increasing penetrative power,opacity, body, and ability to resist running or blurring.

The ink which is to be printed first and which may be considered as thefoundation ink, usually the yellow ink, is made with the heaviest bodyor consistency. The second ink, usually the blue ink is made with aconsistency of about one-half that of the yellow ink. Similarly, thethird ink, usually the red ink, is made with -.a further decreased bodyor consistency, preferably having a viscosity of about one-half that ofthe blue ink.

The following preparation of a yellow ink, a blue ink, and a red ink isintended to be illustrative of one ink series presenting suitablerelative'absorptive character, adapted to effect the complete wetblending of the invention.

A heavy, dense yellow ink is first prepared by mixing ground lead with ayellow dye of a purity such as to provide a paste having a tintapproximately of lemon yellow. The dye employed should be one which hasno red or blue in it. To this'mixture is added a linseed oil ofpronounced drying character, such as a double boiled linseed oil. Anamount of this oil is added suflicient to provide a mass of paste-likeconsistency, which in turn is thinned with a penetrating agent such asturpentine, to provide a thick viscous fluid of a consistency generallyresembling that of honey.

A blue ink is next prepared, using a mineral pigment such as the groundlead above referred to, which is tinted by means of some conventionalblue dye to provide a mass having a shade of blue of the color known asMilory blue. To this mixture is added a linseed oil of a substantiallythinner character than the linseed oil used in connection with theyellow ink, for instance a linseed oil which has been boiled only onceis suitable. The blue mixture thereafter is thinned with a'small amountof materials such as lithographic varnish to provide a viscous fluid ofmuch thinner consistency than the yellow ink described. Preferably anink of about one-half of the viscosity of the yellow ink is provided.

The red ink is prepared from a mineral pigment as used before, such asground lead, and a true red dye containing no yellow or blue is added toit. A red dye of the scarlet type such as alizarin crimson issatisfactory. This mixture is entirely thinned with a relatively thinlinseed oil product such 'as lithographic varnish to provide a'fluid ofabout the consistency of enamel, and preferably of about one-half of theconsistency of the blue ink above described.-

It will be observed that in each of the several inks described, a commonbase of linseed oil with the mineral pigment is employed. However, thebase is utilized in graduated consistencies. In the yellow ink it isused in a very heavy form such as obtained by double boiling; in theblue ink it is. of considerably lighter nature although still somewhatheavy bodied, as obtained by a single boiled linseed oil; and in the redink it is of a still thinner consistency from dilution with thelithographic varnish. The base acts as a vehicle for each of the inksand it provides a medium for rendering each of the inks attractive toone another. It also provides slickness and highly absorbent characterand make POS- sible a very pronounced drying action. The ground lead iseffective in furnishing a highly opaque film, and yet providing a bodywhich may absorb each of the three inks without too great difficulty.The use of turpentine in the yellow ink is to increase penetration andreduce the gloss of the linseed oil.

It is pointed out that the consistencies described for each of theseveral inks cited greatly exceed the consistencies of inks usuallyemployed with intaglio or recessed printing plates. However they have aslickness resulting from the use of the ingredients noted, which it hasbeen found allows a doctor blade to carry out effective removal of suchinks from the non-printing surfaces of an intaglio plate. This abilityof the inks to modify the usual intaglio process may be made use of invarious connections other than blended color work, as for examplejuxtaposed color work and the like. Also other ink series may beresorted to generally adhering to the blending principle of theinvention, the foundation ink or yellow ink may be made of some othercolors, a greater number of colors utilized, and other modificationspracticed.

An important feature of the invention consists in the use of thetransfer member to bring together and blend a series of differentlycolored inks in a wet state. Preferably this. member consists of arubber blanket generally resembling a lithographic blanket. Ithas been.found that a transfer roll of resilient character is effective inpicking up a film of a base or foundation ink, such as the yellow inkdescribed. This film by its thinness, its association with the roll, itsdouble contact with air, or by some other reason, makes possibleblending and release of blended colors successively applied thereto in awet state. The association of inks of the character noted, in theamounts possible from operation of the transfer roll, results in all ofthe colors succeeding the first color becoming completely absorbed inand through the thickness of the yellow ink film. Absorption andblending action which occurs throughout the thickness of the ink filmsoverlying one another, is highly important since it allows the bottom ofthe ink image as it occurs on the'offset blanket to become the top sideof the printed image with true blending of colors being maintained. Thetransfer member, together with the drying agents employed in the inksnoted, cooperate to effect a quick drying of the blended image. Thisdrying effect is developed to a point where the wet blended imageprinted down on a desired surface by the offset operation almostinstantaneously becomes dry.

Several advantages are obtained from the procedures noted. A trueblended color image is obtained and printed in substantially dry state,with very considerable saving of time and materials and improvement inquality. The use of a number of separate offset rolls, as are employedby many conventional color processes, is obviated and one offset rolldoes all of the work. A speed of operation is available, greatly beyondanything now possible with present printing procedures. The use of inksof the character noted in connection with intaglio plates increases thescope of intaglio printing and provides a quality of blended colorprinting of superior character.

If desired, certain procedures may be utilized to further improve theoperations described. For example, the printing plates may be speciallyprepared to provide for varying the amounts of the specially preparedinks which are to be brought etch, which allows the o'f an undercutnature.

together in securing a proper blended effect. This is done by employingdifierent types of screens and etching procedures in the forming of eachof a series of color plates to make differently sized ink depressions.

For example, if a blended color job is to be made of yellow,eblue andred inks of the character described, a-yellow printing plate will firstbe formed in accordance-with some conventional plate making method inwhich a screen is employed. In carrying out the method of plate making arelatively coarse size of screen may be employed. This plate may beetched by a bath etchto be directed squarely into the metal. The platethus prepared is particularly suitable to holding relative large amountsof a heavy foundation ink and to releasing such a heavy ink from itsdepressions. This provides for a foundation film of an opaque characterwhich is well suited to blending of subsequent inks. A second plate. asthe blue ink plate, will then be similarly prepared from a bluephotographic negative, employing a different size of screen, as forinstance one smaller which modifies the ink-receptive character of theplate as a whole as compared with the yellow plate. AIso, a differentetching procedure may be resorted to;

For example, an acid blast etching procedure may be used, which willeffect dots in the metal These dots are adapted to provide for suitableretention of lighter bodied inks such as the blue ink above describedand yet allow for their release on the offset blanket. Similarly, a redplate may be prepared with a still different dot pattern, depth or otherformation, and this plate,in amounts of another type of ink such as thered ink above described, allowing it to be attracted by and absorbedinto films of blue and yellow inks disposed on an oil'set blanket.

I may also desire to employ other types of printing members, as reliefplates, with the special absorbent inks and an offset blanket, to secure my novel blended printing effects. These relief plates may also beformedto collect and retain varying amounts of ink, depending upon thetype of ink which they are to handle, in the same manner as has beendescribed in connection with preparing'a series of gravure color plates.Similarly, combinations of both gravure and relief plates, and relief orplanographic plates, with offset printing members, may be resorted towith respective inks and plates being modified so that they are adaptedto function properly with one another.

Most printing members require a specific type of ink to be usedwiththem. For instance, it is usually necessary to employ, with an intaglioplate, a relatively light ink, which can be easily scraped by a doctorblade, and which may be readily pulled from an intaglio plate by a tackysurface such as that of. paper.- Increasing the body of the ink tends tocause faulty separation of the ink from the plate on to a blanketsurface and to interfere with proper transfer of the ink from theblanket to the surface to be printed upon. This is also particularly thecase in conturn may hold suitable- 1 plying or forming an ink-trappingmedium or film inks, and

on the surface of a given printing member. The mm acts as a carrier forattracting and retaining also as a separating agent for allowing the inkto be readily separated from the printing member and applied to someother surface.

For example, the surface of a transfer blanket of rubber may be treatedto change its ink retentive character by'the application thereto ofcertainorganic materials, which attack the rubber. 0ne substancesuitable for modifying the ink retentive character of a blanket ofrubber is gasoline; another mixture-found to be suitable is onecomposed, of fuel oil, gasoline, and xylol.

Also, mixtures of these and other materials may be utilized in a jellyform. Rubbing over the surface of a blanket with materials such as thesemay change its ink retentive character so that it will take increasedamounts of printing ink, and at the same time allow the blanket totransfer the ink to a relatively more tacky surface such as that ofpaper without any undesirable sticking. By a film such as thatdescribed, an ink is associated with the surface of a plate in the sameway that 25 a greasy ink is lightly disposed over the hygroscopic filmof a planographic printing plate in its non-printing parts before theplate is developed.

In a somewhat similar manner, printing plates as intaglio and reliefplates may be treated with chemical reagent, or someother means to forma film in the engraved parts of the plates. An example of such aprocedure is the use of a mild acid, such as hydrochloric acid, whichwill lightly attack the metal surface of a printing plate and rovide afilm attractive to the ink. Another procedure is to provide an ink ofwater-repellent character and to apply,'in the printing portions of theplate, a film of moisture which tends to keep the ink in a separatedcondition from the metalof the plate, so that it may be readily pulledtherefrom. Other means and reagents for treat- I ing the plates ,bedesired to be employed, as'alkalies, organic to facilitate handling ofink's may materials, and the like.

" a relief plate with an offset nection with transferring a heavy ink ofthe letterpress type from a'relief plate on to a blanket.

Similar difliculty is experienced with substanmembers.

tially all printing According to the invention, these difficulties areminimized by treating the surfaces ofsuch printing members tosubstantially modify their ink handling character. This is effected byap- Modifying the ink retentive character of printing membersisparticularly advantageous in connection with onset pointed out that aplate which is to be used in an offset process must not .only take upink in relatively large amounts, but must also release the ink fairlyreadily to a transfer blanket. The ink. fairly readily and the platemay-be developed bythe method described for' either relief plates,intaglio plates, or other types of plates, or combinations thereof. Theprocedure is also useful with respect to using an exceedingly heavy inkof, usual printing ink character can be Picked up by the films ormediumsdescribed, and effectively released on to a blanket, and thentransferred without the large pressures usually employed to reliefplates. Similarly gravure or intaglio printing can be combined with barswithout-the usual difliculties.

The procedure or principle of treating a surface which is to pick up orhandle an ink may be also extended to ink films themselves as they occuron a printing member." For instance, it is posand develop other effects.It is pointed out that treatment of ink films on a blanket or on a plateprinting procedures. Itis This relative inkprinting plate, since holdsuch inks from offset printing memfilms, it becomes more practical touse one offset blanket for picking up all of a number of colored inksinstead of using separate blankets for eachcolor as is now the custom toa great extent.

It will be seen that novel methods of printing have been disclosed.These methods combine offset printing operations with various types ofprinting plates to broaden the scope of both offset printing and otherprocesses of printing. Procedures for improving inks and printingmembers are indicated. Accurate wet color blending may be quicklyattained, greatly improved drying effects are arrived at, and a cheaper,simpler, and more efficient printing procedure is made available.

While there has been described a preferred embodiment of the invention,it should be understood that various other applications of the means andprocedures disclosed may be resorted to and other reagents and materialsemployed in connection with various types of printing plates in keepingwith the spirit of the invention.

Having described my invention, I claim:

1. That improvement in methods of printing which consists in applying onan offset printing member a dense absorbent printing ink, selectivelyapplying over the first inkwhile wet a second differently coloredprinting ink of a relatively thinner consistency adapted to penetrateinto the first ink and form blended color parts throughout the thicknessof the layer of the said first ink, then again selectively applying overthe first and second inks while wet a third differently colored printingink of a consistency different than that of either of the saidfirst andsecond inks and adapted to be absorbed by each of the said first andsecond inks, thereby to effect further blending throughout the thicknessof the layers of each of the said first and second inks, and thenoffsetting the blended inks in a wet state upon a-surface to be printed,to provide a substantially dry printed, blended color image.

2. That improvement in methods of printing which consists in applying onan offset printing member a layer of a dense absorbent printing inkhaving a base of a highly polymerized drying oil, selectively applyingover the first ink while wet a second differently colored printing'inkwhich has a base 'of a drying oil of a relatively thinner viscosityadapted to blend with the first ink layer throughout its thickness, thenagain selectively applying over the first and second inks while wet athird differently colored printing ink which has a base of a drying oilthinner than the oils of the first and second inks, said third ink beingadapted to blend throughout the thickness of the layers of the first andsecond inks, and then offsetting the blended inks in a wet state upon asurface to be printed to provide a substantially dry blended colorimage.

31 That. improvement in methods of printing which consists in applyingon an offset printing member a dense absorbent printing ink having avehicle of a highly polymerized linseed oil, selectively applying overthe first ink while wet a seccolored printing ink of a differentviscosity than that of either of the said first and second inks andhaving a vehicle of a linseed oil of a character thinner than thelinseed oil.vehi cles employed in said first and second inks, for thepurpose of effecting blending of the third ink throughout the thicknessof the layers of the first and second inks, and then'offsetting theblended inks in a wet state upon a surface to be printed to provide ablended color image.

4. That improvement in methods of blended color printing which consistsin preparing a series of printing inks of graduated absorptivecharacter, forming a series of printing plates for a' given multi-colorsubject matter to be printed, with differently sized screens anddifferently applied etching materials to form recessed areas ofrespective plates of graduated ink receptive character, inking theplates in a definite sequence in which the most absorptive ink of thesaid series is applied to the plate of greatest ink receptive character,then treating the surface of a transfer printing member to increase itsink receptivity, applying the most absorbent ink of the series on thetreated surface of the transfer member, then applying, in a wet state,the remaining inks in order of their absorptivity oneupon another, and

then oifsetting the severalinks in a blended substantially dry state.

5. That improvement in methods of printing which consists in providing aseries of differently colored printing inks absorbent one to another,preparing a series of intaglio printing plates for each of the coloredinks, the recessed parts of the plates being modified by the use ofvarying sized screens and etching procedures in accordance with therespective ink which each plate is to accept, combining on a transfermember superimposed layers of the colored printing inks in wet blendedcolor relation throughout the thickness of each of the layers, and thenoffsetting the blended inks.

6. That improvement in methods of printing which consists in providing aseries of differently colored printing inks, of different degrees ofabsorbency, forming on a transfer member a film receptive to themostabsorbent ink of the said series, then collecting on the film-coatedtransfer member the said inks in order of their absorbency, and thenoffsetting the blended image.

'7. That improvement in methods of printing which consists in providinga series of intaglio plates, each of said plates being etched inaccordance with differently sized screens, inking said plates with aseries of inks which are absorptive' one with another, applying saidinks one upon another from said plates on to a resilient transfer memberin a wet state, and offsetting the inks to comprise a blended printingimage.

8. That improvement in methods of color printing which consists insuccessively superimposing in a definite sequence on an offset blanket anumber of wet colored inks of graduated absorptivity with respect to oneanother-to form an image in which blending occurs throughout thethickness of each of the layers of color, and then offsetting.

. which 10. That improvement with respect to one one 11. Thatimprovement in methods or printing which consists in developing on thesurface 01' a I wet printing inks, and then offsetting the blended inks.

- JoHN J. QRMOND.

